The present invention concerns a method for adjusting or setting a transmitter carrier frequency in a subscriber station of a point-to-multipoint radio transmission system, in which a base station is provided with as many modems as the maximum number of subscriber stations that can be connected with it and similarly each subscriber station has a modem.
This sort of point-to-multipoint radio transmission system is described in the unpublished German Patent Application 196 355 33.8. In this radio transmission system communication between the base station and the individual subscriber stations occurs by frequency division multiple access (FDMA). Thus the flexible transmission capacity is designed for the needs and number of the subscribers, since the bandwidth of the individual transmitter channels is adjusted to the data transmission rate required by the respective individual subscribers stations. Flexible assignment and adjustment of the transmission capacity is possible in the connected subscriber stations without interference and interruption. Also every modem in the base station and in the individual subscriber stations has at least two transmitter and at least two receiver channels, and the signal transmission between the base station and one of the subscriber stations occurs first only over one transmitter and receiver channel. When the transmitter channel is changed, a control device sets the new transmission parameters (channel carrier frequencies, data rate, modulation, coding and transmitter signal level) in the at least one transmitter or receiver channel not found in operation, while the signal transmission in the other transmitter or receiver channel is continued. After finishing acquisition of the channel with the new transmission parameters switching to the transmitter or receiver channel not previously in operation occurs.